Transmitter



, A. LAUTERER 1 TRANSMITTER May 27', 1930.

Fild July 24,' 1928 Inventor:y

Anfon Letevjer Attorney Patented May 27, 1930 UNITED STATES PATENT OFFICE ANTON LAUTERER, F BERLIN-SCHONEBERG, GERMANY, ASSIGNOIR T0 C. LORENZ AKTIENGESELLSCHAFT, 0F BERLIN-TEMPELHOF, GERMANY TRANSMITTER Application led July 24, 1928, Serial No. 295,084, and in Germany Janualy 21, 1928.

The present invention refers to an undamped transmitter, the diaphragm o which is provided with a nipple. The electrode of the unda'mped transmitter is equipped with a rin projecting into the carhon-powder. "-Here y the burnin of the carbon-powder is avoided, which urning may happen when-at the moment of taking up the receiver-ringing-current impulses pass the microphone. When-at such a momenta ga is formed between the diaphragm an the carbon-powder, or the electrode and the carbon-powder, the current may take its way through particles of carbon adhering to the diaphragm and its felt-ring or at the electrode. By those momentarily strong impulses these particles become red hot and are destroyed. In order to do away with this drawback transmitters have already been created the diaphragmsof which are equipped with nipples and the electrodes with rings projecting into the carbon-powder.

These well known transmitters, however, are subject to certain inconveniences. It may happen, thatV single particles at vthe diaphragm and at the electrode of the transmitter may begin to burn and destroy the feltring enveloping the powder. Besides, by this felt-ring enveloping` the owder the microphone itself is damped, an such microphones are not very eicient. f

The present invention, now, has for its object a transmitter which avoids these detrimental inconveniences of the transmitters lmown. This is reached by enclosing the carbon grains or powder in a capsule covered by a plate, through which latter the nipple of the diaphragm projects into the mass of the carbon-powder.

The drawing annexed is a practical example of the invention partly in section and partly in elevation. The diaphragm 1 has a conical-ended nip le. 2. It 1s clamped into a casing 7 covere on its top by a disk 8 in the usual way. The capsule or chamber 4 containing the carbon-powder 3 is fixed on a The disk 5 made of insulating material.

electrode 6 which is mounted within the capsule 4 is provided with aA ring or annular v projection 6'., This latter may. be fixed to the electrode or the entire electrode including the ring may be made of one piece of material. The most advantageous constellation is when the layer of carbon-powder between the cone surface ofthe nipple 2 and the 55 ring of the electrode 6 is equally thick at all points. This is the case when the mantleline of the nipple 2 is in parallel with the oblique face of the ring of the electrode I6. In that case the layer of carbon-powder between these two surfaces offers an equal resistance at every pointI and current passes everywhere, and not merely at the top of the nipple.

The felt-ring 10 is arranged between the 65 cover-plate 9 ofcapsule 4 and the diaphragm 1. This felt-ring` is very small in size and the microphone is not damped by it. The cover-plate 9 of capsule 4 is provided with a hole of sufficient size as to allow a'free oscillation of the nipple 2.

Capsule 4 may effectively be lined with a hard insulating substance. This substance v may, for instance, be mica. `It is preferred to use a hard insulating substance in order to prevent deleterious consequences in case single carbon-particles should unavoidably be burned in consequence of the presence of strong currents.

What I claim is:

1. An undamped transmitter em loying carbon powder and having means fldr preventing burning of the carbon granules, comprising a diaphragm, a capsule enclosing the body of carbon-powder, an electrode in said capsule, a plate closing the side of said capsule facing the diaphragm and having an opening therein, a nipple on the diaphragm extending loosely into the capsule and body of carbon-powder therein through thev opening in said plate, and means for closing the ioint between the nipple and wall of the opening against the escape of the carbon granules. 5

2. An undamped transmitter em loying carbon owder and having means or pre-J venting urning of the carbon granules comprising a diaphragm, a capsule enclosing the body of carbon-powder, an electrode in said capsule, a plate closing the side of said cap- 100 sule facing the diaphragm and having an opening therein, a nipple on the diaphragm having a portion of uniform diameter-proj ecting through the opening in the plate and terminating 1n a conical portion loosely extending into the body of carbon-powder, and a felt-ring enclosing the portion of the nipple of uniform diameter between said plate and said diaphragm and closin the joint` between the nipple and .wall o the opening in the' plate against the escape of carbon particles.

'3. An undamped transmitter employing carbon granules and having means venting burning of the carbon granules compr1sing a dia hra a ca sule enclosfp ttiing the body car pow er, an electrode in said capsule and provided with a conducting 'ring projecting into the body of car bon powder2 a plate covering the side of the capsule 'faclng the diaphragm and having an opening therein, a nipple on the diaphragm extending loosely through said openmg and into the carbon-powder in the capsule and a felt-ring enclosing the nipple between said plate and said diaphragm and closin the joint between the nipple and wall of sai opening in the plate.

In testimony whereof I have aixed my signature f ANTON LAUTERER.

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